Marijuana Water Pipe and Vaporizer Study

September 21, 2000 update: MAPS and CA-NORML are sponsoring a
new vaporizer study. Testing and data analysis have been completed. A detailed report
will be issued soon. The design and cost of additional studies are currently
being discussed with the analytical lab.

The new study is a $25,000 proof of principle study designed to determine if
marijuana vaporizers can indeed reduce particulate matter and carbon monoxide
as compared to the combustion of marijuana. We have a very high-tech lab
doing the research, but unfortunately the lab wants to remain anonymous. They
are concerned about becoming known as a place with marijuana (all they have
is 5 grams!), but the major reason for their reluctance to get publicity is
due to industrial espionage. They do lots of work for major pharmaceutical
companies who want discretion, so they don't advertise. I was personally
recommended to them by an organic chemistry company that is making psilocybin
for MAPS for a U. of Arizona study of psilocybin in the treatment of OCD.

Anyway, the results of the vaporizer study do show substantial reductions in
particulate matter and in carbon monoxide. I conceive of this study as
contributing to the argument in favor of permitting patients to grow and use
their own marijuana, instead of having to purchase patented, FDA-approved
cannabinoid or marijuana-extract products from Unimed or GW Pharmaceuticals.
Vaporizers are the only non-smoking marijuana delivery systems that can be
used with home-grown marijuana. We are trying to create evidence to show that
there is a favorable risk/benefit ratio from using high-potency marijuana in
vaporizers.

The main tradeoffs that patients will face are slightly highly but probably
not clinically significant health risks but lower price from high-potency
marijuana delivered in vaporizers as compared to Unimed or GW products.
Efficacy will probably be similar. The health effect of wealth (the impact on
the health of patients from the extra money they save from using home-grown
in vaporizers as compared to other products) will, perhaps, outweigh the
additional health risks. This is all speculative and there is certainly a
major need for FDA-approved products that can be paid for by insurance, since
home-grown used with vaporizers will probably not become approved by FDA
anytime soon, at least not in the current political climate.

Contrary to popular impression, waterpipes don't necessarily protect
smokers from harmful tars in marijuana smoke, according to a new study
sponsored by MAPS and California NORML (National Organization for the
Reform of Marijuana Laws). The reason is that waterpipes filter out more
psychoactive THC than they do other tars, thereby requiring users to smoke
more to reach their desired effect. The study does not rule out the
possibility that waterpipes could have other benefits, such as filtering
out gases, but it suggests that other methods, such as the use of high
potency marijuana, vaporizers, or oral ingestion are needed to avoid
harmful toxins in marijuana smoke.

Seven Devices Tested

The study, which was supported by the Drug Policy Foundation and private
donors, was conducted at a research lab with expertise in the analysis of
various chemical properties of tobacco and marijuana. Researchers tested
the smoke from seven different sources: a regular rolled joint, a joint
with a cigarette filter, three different waterpipes, and two vaporizers,
designed to heat marijuana to a temperature where psychoactive vapors form
without producing smoke.
The waterpipes included a standard bong (Picture
#1), a small portable device with a folding
pipestem (Picture #6), and a
battery-operated model with a motorized paddle to thoroughly mix the smoke
in the water (Picture #3). The first vaporizer
(Picture #5), commercially
produced in Canada, consisted of a battery-powered metal hot plate inside
a jar to trap the marijuana vapor. The second
(Picture #4) was a
homemade, hybrid apparatus, in which vapors were produced by a hot air gun
and then drawn through a beaker of water, thereby combining vaporization
with water filtration. The smoke was produced from standard NIDA-supplied
marijuana drawn through a smoking machine adjusted to mimic the puff
length of marijuana smokers.

The study focused on two key components of the smoke: (1) total solid
particulates, or tars, which are noxious waste by-products of burning leaf
like those from tobacco; and (2) cannabinoids, the chemicals distinctive
to marijuana, including its major psychoactive ingredient,
delta-9-tetrahydrocannabinol (THC), and its two commonest chemical
relatives, cannabinol (CBN) and cannabidiol (CBD), which are only weakly
psychoactive but may have medical benefits.

Like tobacco, marijuana tars are rich in carcinogenic compounds known as
polycyclic aromatic hydrocarbons, which are a prime culprit in
smoking-related cancers. However, cannabinoids themselves are not
carcinogenic. An obvious way to protect smokers' health is therefore to
minimize the content of smoke tars relative to cannabinoids.

One way to do this is to increase the THC potency of the marijuana.
Assuming smokers adjust their smoke intake to the cannabinoid dosage, the
higher the concentration of cannabinoids, the lower the amount of tars
they are likely to consume.

Another strategy is to try to reduce the tars in the smoke with some kind
of filtering device. Obviously, this is beneficial only to the extent that
THC isn't also reduced, thereby inducing users to smoke more to
compensate. A major aim of the study was to determine the efficacy of
various smoking devices at reducing the concentration of tars relative to
cannabinoids. The performance of each device was accordingly rated in
terms of the cannabinoid-to-tar ratio in its smokestream.

Surprisingly, the unfiltered joint outperformed all devices except the
vaporizers, with a ratio of about 1 part cannabinoids to 13 parts tar.
This disturbingly poor ratio may be explained by the low potency of the
NIDA-supplied marijuana used in the study, which was around 2.3%.

Disappointingly, waterpipes performed uniformly worse than the unfiltered
joint. The least bad waterpipe, the bong, produced 30% more tar per
cannabinoids than the unfiltered joint. Ironically, the pipe with the
electric mixer scored by far the worst of any device. This suggests that
water filtration is actually counterproductive, apparently because water
tends to absorb THC more readily than noxious tars. Like the waterpipes,
the cigarette filter also performed worse than the unfiltered joint, by
about 30%. Researchers speculate this is because cannabinoids are
exceptionally sticky and adhere to other solids. Hence, any filtration
system that picks up particulates is likely also to screen out
cannabinoids.

Vaporizers

The vaporizer results appeared more promising, but confusing. The two
vaporizers were the only devices to outscore unfiltered joints in terms of
raw cannabinoid/tar ratio. The electric hotplate vaporizer did best, with
a performance ratio about 25% higher than the unfiltered joint. The hot
air gun was just marginally superior, but might have done better had it
not been for its water filtration component.

However, the situation was complicated by the fact that the cannabinoids
produced by the electric hotplate vaporizer were unusually high in CBN,
leaving 30% less THC as a percentage of the total cannabinoids than with
the other smoking devices. Since CBN is not psychoactive like THC,
recreational users might be expected to consume more smoke to make up for
the deficit. (The situation may be different for medical users, who could
experience other, medicinal benefits from CBN). For this reason, it seemed
advisable to recompute the performance efficiencies of the vaporizers in
terms of THC, rather than all cannabinoids. When this was done, the
electric hotplate vaporizer turned out to have a lower THC/tar ratio than
the unfiltered joint, while the hot air gun was still marginally
higher.

The reason for the excess CBN from the hotplate vaporizer remains
unexplained. Because CBN is produced from THC by chemical oxidation, it
has been suggested that the device somehow exposed the sample to too much
oxygen. However, there is no evidence that this was the case. As for the
second, hybrid vaporizer, it seems likely that its performance could have
been improved by deleting its water component.

The results clearly indicate that more developmental work needs to be done on vaporizers. Theoretically, an ideal vaporizer could minimize production
of tars by holding the temperature above the point at which THC vaporizes, but
below that where carcinogenic hydrocarbons are produced by combustion
[Note] In practice, both vaporizers produced
over ten times more tars than cannabinoids, indicating that there is plenty of room for improvement.

In the late 1970s, a vaporizer known as the Tilt appeared on the market.
According to the manufacturer, laboratory tests showed that it released
80% more THC and 79% less tar than a regular pipe, a performance ratio
almost ten times better than any observed in this study. It is to be hoped
that these impressive results can be replicated in the future.
Unfortunately, the Tilt was withdrawn from the market in the early 1980s
due to the passage of anti-paraphernalia laws.

As for waterpipes, the prospects for improvement appear more dubious. It
has been suggested that the performance of waterpipes could be improved by
using liquids other than water or by changing the temperature of the
liquid. However, it seems doubtful whether such tactics would circumvent
the basic problem of separating the tars from the sticky cannabinoids.

Are Waterpipes Counterproductive?

The study results are obviously discomforting to waterpipe enthusiasts,
many of whom prefer the cooler, milder smoke they produce, and have
naturally assumed it is also more healthful. Unfortunately, however, the
study indicates that waterpipes may actually be counterproductive in
increasing consumption of carcinogenic tars.

Nonetheless, it is still premature to judge that waterpipes are actually
unhealthful, since they may filter out other, non-solid smoke toxins
occurring in the gas phase of the smoke, which was not analyzed in the
study. Noxious gases known to occur in marijuana smoke include hydrogen
cyanide, which incapacitates the lung's defensive cilia; volatile phenols,
which contribute to the harshness of the taste; aldehydes, which promote
cancer; and carbon monoxide, a known risk factor in heart disease.
Previous studies indicate that water filtration may be quite effective in
absorbing some of these [Nicholas Cozzi, Effects of Water Filtration on
Marijuana Smoke: A Literature Review, MAPS Newsletter, Vol. IV #2, 1993].
If so, waterpipes might still turn out to have net health benefits.

MAPS and California NORML are planning to undertake a second phase of the
waterpipe study for the purpose of analyzing the gaseous phase of
marijuana smoke.

In the meantime, the easiest way for most smokers to avoid harmful smoke
toxins may be simply to smoke stronger marijuana. This strategy is apt to
be more effective than any smoke filtration device. By simply replacing
the low, 2.3% potency NIDA marijuana used in this study with high-quality
12%-sinsemilla, smokers could presumably reduce their tar intake by a
factor of five while still achieving the same effect. Further improvements
could be had by using pure THC or hash oil, which has been tested at
potencies of 60%.

The notion that high-potency marijuana is less harmful directly
contradicts official government propaganda, which maintains that marijuana
has become more dangerous since the '60s due to increased potency. This
claim appears to rest less on scientific evidence than on the desire to
frighten the public. A careful analysis of government data by Dr. John
Morgan has shown that the supposed increase in potency has been greatly
exaggerated [American Marijuana Potency: Data Versus Conventional Wisdom,
NORML Reports (1994)]. In any case, however, there is no good reason to
presume that higher potency marijuana is more harmful, given the potential
respiratory benefits of reduced smoke consumption. The hazards of
excessive potency are purported to be an increased risk of acute overdose
and greater susceptibility to dependency. However, both problems can be
avoided if users adjust their dosage to potency. For most users, such
hazards may well be outweighed by the benefits of reduced smoke
consumption.

Research in Australia

The Australian government is currently conducting another study that may
cast further light on the effects of potency variations. The study is
designed to determine baseline THC, tar, and carbon monoxide levels from
marijuana and marijuana-tobacco mixtures smoked through joints and
waterpipes. The samples being tested come from police seizures in six
different Australian states. Researchers say that they have observed
"incredible" variations in tar and THC potency among different
samples. Their report is expected shortly.

THC Transfer Rate

The MAPS-NORML study provides new information on the efficiency of
different devices in delivering THC from marijuana to the user. Previous
studies have shown that 60% - 80% of the THC burned in joints or
waterpipes is lost in slipstream smoke, adhesion to the pipestem and bowl,
pyrolysis, etc. [Mario Perez-Reyes, Marijuana Smoking: Factors that
Influence the Bioavailability of Tetrahydrocannabinol, in C. Nora Chiang
and Richard Hawks, ed., Research Findings on Smoking of Abused Substances,
NIDA Research Monograph 99, 1990]. The percentage of total THC delivered
to the user is called the THC transfer rate. The unfiltered joint scored
surprisingly well in smoking efficiency, coming in second place with a
transfer rate close to 20%. The portable waterpipe did slightly better,
and the bong slightly worse. The other devices did notably worse. The
vaporizers and electric waterpipe did especially poorly, with transfer
rates less than one-third that of the top three devices. Thus, heavy
smokers could literally be blowing most of their stash away with bad
pipes.

Note:
Contrary to the initial version of this article, which erroneously stated that THC vaporizes at 155º C, the Merck
Manual lists the vaporization point of THC as 200º in vacuum. The vaporization point at normal atmospheric pressure
appears to be unknown, but is thought to be in the range 250-400º.